:root {
            --primary: #00d294;
            --primary-deep: #009d6b;
            --primary-soft: rgba(0, 210, 148, 0.12);
            --accent: #00c6ff;
            --bg-root: #0b0f19;
            --bg-card: #151c2c;
            --bg-card-hover: #1b2338;
            --bg-lift: #1a2234;
            --text-main: #ffffff;
            --text-sub: #94a3b8;
            --text-muted: #64748b;
            --border-color: rgba(255, 255, 255, 0.07);
            --border-glow: rgba(0, 210, 148, 0.25);
            --radius-lg: 16px;
            --radius-md: 10px;
            --radius-sm: 8px;
            --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.3);
            --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Noto Sans SC", sans-serif;
            background-color: var(--bg-root);
            color: var(--text-main);
            line-height: 1.6;
            overflow-x: hidden;
            -webkit-font-smoothing: antialiased;
        }

        a {
            text-decoration: none;
            color: inherit;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 24px;
        }

        /* HEADER */
        header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin: 20px auto;
            padding: 20px 0;
            border-bottom: 1px solid var(--border-color);
            position: relative;
            z-index: 10;
        }
        .brand {
            display: flex;
            align-items: center;
            gap: 12px;
            font-size: 22px;
            font-weight: 800;
            letter-spacing: -0.5px;
            transition: var(--transition);
        }
        .brand:hover {
            opacity: 0.85;
        }
        .brand-icon {
            width: 38px;
            height: 38px;
            background: linear-gradient(135deg, var(--primary), #0091c7);
            border-radius: 10px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 18px;
            font-weight: 800;
            color: #fff;
            box-shadow: 0 4px 14px rgba(0, 210, 148, 0.3);
        }
        .version-badge {
            font-size: 10px;
            background: var(--primary-soft);
            color: var(--primary);
            border: 1px solid rgba(0, 210, 148, 0.35);
            padding: 3px 10px;
            border-radius: 20px;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            font-weight: 600;
        }
        nav ul {
            display: flex;
            list-style: none;
            gap: 34px;
            align-items: center;
        }
        nav a {
            font-size: 14.5px;
            color: var(--text-sub);
            transition: var(--transition);
            position: relative;
            padding: 6px 0;
            font-weight: 500;
        }
        nav a::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            width: 0;
            height: 2px;
            background: var(--primary);
            border-radius: 2px;
            transition: width 0.3s ease;
        }
        nav a:hover,
        nav a.active {
            color: #fff;
        }
        nav a:hover::after,
        nav a.active::after {
            width: 100%;
        }

        /* PAGE HEADER */
        .faq-header {
            text-align: center;
            padding: 54px 0 30px;
        }
        .faq-header h1 {
            font-size: 44px;
            font-weight: 900;
            margin-bottom: 14px;
            letter-spacing: -1px;
        }
        .faq-header h1 span {
            background: linear-gradient(135deg, var(--primary), #00e5ff);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        .faq-header p {
            color: var(--text-sub);
            font-size: 16px;
            max-width: 640px;
            margin: 0 auto;
            line-height: 1.6;
        }

        /* 搜索框（装饰性） */
        .search-box {
            max-width: 500px;
            margin: 0 auto 36px;
            position: relative;
        }
        .search-box input {
            width: 100%;
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            border-radius: 30px;
            padding: 12px 48px 12px 20px;
            color: var(--text-main);
            font-size: 14px;
            outline: none;
            transition: var(--transition);
        }
        .search-box input::placeholder {
            color: var(--text-muted);
        }
        .search-box input:focus {
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(0, 210, 148, 0.15);
        }
        .search-box .search-icon {
            position: absolute;
            right: 16px;
            top: 50%;
            transform: translateY(-50%);
            font-size: 18px;
            color: var(--text-sub);
            pointer-events: none;
        }

        /* 分类按钮 */
        .faq-categories {
            display: flex;
            justify-content: center;
            gap: 12px;
            margin: 0 0 50px;
            flex-wrap: wrap;
        }
        .cat-btn {
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            color: var(--text-sub);
            padding: 10px 22px;
            border-radius: 30px;
            font-size: 13.5px;
            font-weight: 600;
            transition: var(--transition);
            cursor: pointer;
        }
        .cat-btn:hover,
        .cat-btn.active {
            background: var(--primary-soft);
            border-color: var(--primary);
            color: var(--primary);
        }

        /* 创意版块：热问速答 */
        .hot-questions {
            margin-bottom: 60px;
        }
        .hot-questions h3 {
            font-size: 24px;
            font-weight: 800;
            text-align: center;
            margin-bottom: 24px;
        }
        .hot-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 18px;
        }
        .hot-card {
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            border-radius: var(--radius-lg);
            padding: 24px 20px;
            transition: var(--transition);
            position: relative;
            overflow: hidden;
            cursor: default;
        }
        .hot-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 4px;
            height: 100%;
            background: var(--primary);
            opacity: 0;
            transition: opacity 0.3s;
        }
        .hot-card:hover {
            border-color: rgba(255,255,255,0.15);
            background: var(--bg-card-hover);
            transform: translateY(-3px);
        }
        .hot-card:hover::before {
            opacity: 1;
        }
        .hot-card .hot-icon {
            font-size: 28px;
            margin-bottom: 10px;
            display: block;
        }
        .hot-card h4 {
            font-size: 16px;
            font-weight: 700;
            margin-bottom: 6px;
        }
        .hot-card p {
            font-size: 13px;
            color: var(--text-sub);
            line-height: 1.5;
        }

        /* FAQ 列表 */
        .faq-grid {
            display: flex;
            flex-direction: column;
            gap: 18px;
            max-width: 900px;
            margin: 0 auto 70px;
        }
        .faq-item {
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            border-radius: var(--radius-lg);
            padding: 26px 28px;
            transition: var(--transition);
            box-shadow: var(--shadow-card);
        }
        .faq-item:hover {
            border-color: rgba(255, 255, 255, 0.15);
            background: var(--bg-card-hover);
            transform: translateY(-2px);
        }
        .faq-item h3 {
            font-size: 17.5px;
            font-weight: 700;
            margin-bottom: 10px;
            display: flex;
            align-items: center;
            gap: 10px;
        }
        .faq-item h3 span.q-badge {
            background: var(--primary-soft);
            color: var(--primary);
            font-size: 13px;
            padding: 3px 10px;
            border-radius: 6px;
            border: 1px solid var(--primary);
            font-weight: 700;
            flex-shrink: 0;
        }
        .faq-item p {
            color: var(--text-sub);
            font-size: 14.5px;
            line-height: 1.7;
            padding-left: 36px;
        }

        /* 创意版块：故障自检助手 */
        .self-check {
            background: var(--bg-card);
            border: 1px solid var(--border-color);
            border-radius: var(--radius-lg);
            padding: 40px;
            margin-bottom: 70px;
            text-align: center;
        }
        .self-check h3 {
            font-size: 24px;
            font-weight: 800;
            margin-bottom: 8px;
        }
        .self-check .subtitle {
            color: var(--text-sub);
            font-size: 14px;
            margin-bottom: 32px;
        }
        .check-steps {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 20px;
        }
        .check-step {
            background: rgba(255,255,255,0.02);
            border: 1px solid var(--border-color);
            border-radius: var(--radius-md);
            padding: 24px 18px;
            transition: var(--transition);
        }
        .check-step:hover {
            border-color: rgba(0,210,148,0.25);
            background: var(--bg-lift);
            transform: translateY(-3px);
        }
        .check-step .check-icon {
            font-size: 32px;
            margin-bottom: 12px;
            display: block;
        }
        .check-step h4 {
            font-size: 16px;
            font-weight: 700;
            margin-bottom: 6px;
        }
        .check-step p {
            font-size: 13px;
            color: var(--text-sub);
            line-height: 1.5;
        }

        /* 联系支持卡片 */
        .contact-support-card {
            background: linear-gradient(105deg, rgba(0,210,148,0.08) 0%, rgba(0,180,220,0.08) 100%);
            border: 1px solid rgba(0, 210, 148, 0.25);
            border-radius: var(--radius-lg);
            padding: 40px;
            text-align: center;
            max-width: 900px;
            margin: 0 auto 100px;
        }
        .contact-support-card h3 {
            font-size: 22px;
            font-weight: 800;
            margin-bottom: 8px;
        }
        .contact-support-card p {
            color: var(--text-sub);
            font-size: 14px;
            margin-bottom: 22px;
        }
        .btn-support {
            background: var(--primary);
            color: #000;
            font-weight: 700;
            padding: 12px 30px;
            border-radius: 8px;
            display: inline-block;
            transition: var(--transition);
        }
        .btn-support:hover {
            background: var(--primary-deep);
            transform: translateY(-2px);
            box-shadow: 0 8px 18px rgba(0, 210, 148, 0.3);
        }

        /* FOOTER */
        footer {
            background: #070a10;
            border-top: 1px solid var(--border-color);
            padding: 56px 0 28px;
        }
        .footer-grid {
            display: grid;
            grid-template-columns: 2fr repeat(3, 1fr);
            gap: 40px;
            margin-bottom: 44px;
        }
        .footer-about p {
            color: var(--text-sub);
            font-size: 13.5px;
            margin-top: 14px;
            max-width: 300px;
            line-height: 1.7;
        }
        .footer-col h4 {
            font-size: 14.5px;
            margin-bottom: 18px;
            color: var(--text-main);
            font-weight: 700;
        }
        .footer-col ul {
            list-style: none;
        }
        .footer-col li {
            margin-bottom: 11px;
        }
        .footer-col a {
            color: var(--text-sub);
            font-size: 13.5px;
            transition: color 0.2s;
        }
        .footer-col a:hover {
            color: var(--primary);
        }
        .footer-bottom {
            border-top: 1px solid var(--border-color);
            padding-top: 26px;
            text-align: center;
            font-size: 13px;
            color: var(--text-muted);
        }

        /* RESPONSIVE */
        @media (max-width: 1024px) {
            .hot-grid {
                grid-template-columns: repeat(2, 1fr);
            }
            .check-steps {
                grid-template-columns: 1fr 1fr 1fr;
                gap: 14px;
            }
            .footer-grid {
                grid-template-columns: repeat(2, 1fr);
            }
        }
        @media (max-width: 640px) {
            header {
                flex-direction: column;
                gap: 14px;
            }
            nav ul {
                gap: 16px;
                flex-wrap: wrap;
                justify-content: center;
            }
            .faq-header h1 {
                font-size: 30px;
            }
            .hot-grid {
                grid-template-columns: 1fr;
            }
            .check-steps {
                grid-template-columns: 1fr;
            }
            .faq-grid {
                gap: 14px;
            }
            .faq-item h3 {
                font-size: 16px;
            }
            .faq-item p {
                padding-left: 0;
                margin-top: 8px;
            }
            .footer-grid {
                grid-template-columns: 1fr;
                gap: 24px;
            }
            .self-check {
                padding: 28px 20px;
            }
            .contact-support-card {
                padding: 28px 20px;
            }
        }